Roadblocks to what? Getting a scientific theory accepted? The peer review process favors researchers who are established in their field, which can be somewhat unfair.

This can tend to be a closed society that is reluctant to accept new ideas and researches outside their chosen field.

Major scientific discoveries and theories by Wegener (of tectonic late motion) and Alvarez (of the massive extinction probably caused by an asteroid 65 million years ago) were not accepted for many years because the scientists were not geologists, and were resented.

The first paper on a working visible light laser, by Maiman, was rejected by Physical Review Letters, a leading journal, possibly because he worked in industry and was not an established academic. The importance and newness of lasers were not believed by the editors of the journal. Maiman's work was later published by the equally prestigious British journal Nature.